precision mediump float;
uniform sampler2D vTexture;
uniform sampler2D uLutSampler;
varying vec2 aCoord;
void main() {
    vec4 texColor = texture2D(vTexture, aCoord);
    float blueColor = texColor.b * 63.0;
    vec2 quad1, quad2;
    quad1.y = floor(floor(blueColor) / 8.0);
    quad1.x = floor(blueColor) - (quad1.y * 8.0);

    quad2.y = floor(ceil(blueColor) / 8.0);
    quad2.x = ceil(blueColor) - (quad2.y * 8.0);

    vec2 texPos1, texPos2;
    texPos1.x = (quad1.x * 0.125) + 0.5/512.0 + (0.125 - 1.0/512.0) * texColor.r;
    texPos1.y = (quad1.y * 0.125) + 0.5/512.0 + (0.125 - 1.0/512.0) * texColor.g;
    texPos2.x = (quad2.x * 0.125) + 0.5/512.0 + (0.125 - 1.0/512.0) * texColor.r;
    texPos2.y = (quad2.y * 0.125) + 0.5/512.0 + (0.125 - 1.0/512.0) * texColor.g;

    vec4 newColor1 = texture2D(uLutSampler, texPos1);
    vec4 newColor2 = texture2D(uLutSampler, texPos2);

    vec4 newColor = mix(newColor1, newColor2, fract(blueColor));
    gl_FragColor = newColor;
}